Resilient joints, more particularly for motor vehicle suspension



Aprilvv 28;. 1,964- R. FuRAcalNofr 3511305991 RESILIENT JorNTs, MOREPARTICULARLYy FOR" MOTOR: VEHICLE SUSPENSION Fileduan. so; 1962whats-sheet 2 April 28 '11964 va. PlRAGlNo 3,'i1l3Q;9L9.-,1

.msm-ENT JorN'rs, MORE PARTICULARLY ma MoToR .VEHLGLE .SUSPENSION Fil-edJan. so, ,1952 4 fsneemssheent 1s April 28, 1964 R. FIRAGINO 3,130,991

RESILIENT JOL'NTS, MORE PARTICULARLY 'FOR MOTOR VEHEECLLE SUSPENSIONFiled Jan. 30, 1962 -4 ySheets-Shards, y4

United States Patent 3,130,991 RESLEENT MENTS, MURE PARTHCULARLY FORM0101?. VEHCLE SUSPENSlN Renato Piragino, Turin, italy, assigner to PV@meine di Villar Perosa Societa per Azioni, Turin, italy Filed Jan. 30,1962, Ser. No. 1o9,75 Claims priority, application Italy Feb. 7, 1961 7Claims. (Cl. 287-85) This invention relates to resilient joints, moreparticularly for motor vehicle suspensions, of the type sometimesreferred to as sliding resilient joints, comprising a bushing having asleeve of rubber or similar elastomer lined with a tubular layer ofantifriction antiwear synthetic resin such as polyamide,polyfluorocarbon or the like.

In an articulation incorporating such a resilient joint having aneye-shaped member receiving the rubber sleeve and a circular-cylindricalpin inserted into the axial bore in the articulation, the pin isslidingly rotatable in the articulation so that angular movements of thearticulation about the axis of the pin do not result in resilientreactions by the sleeve. In this connection advantage is taken of theself-lubricating and antiwear properties oi the synthetic resin liningin sliding engagement with the pin.

Since such properties are never quite satisfactory or durable inpractice, it was previously attempted to provide for additionallubrication of the surfaces in sliding interengagement by introducingtherebetween a suitable lubricant (grease, graphite or the like) and byproviding a supply of lubricant within suitable recesses in the elementsof the articulation. Structures of this type known heretofore are notcurrently used, for the desired lubrication of the interengagingsurfaces failed after a very short operational period.

The main object of this invention is to provide a resilient slidingself-lubricating joint of improved life, which obviates theabovementioned drawback.

According to this invention the inner surface of the tubular layer ofsynthetic resin is polygonal in cross sectional shape. The rubber sleevehas at least one flanged end having on its front or outward face anannular outwardly flaring layer of antifriction antiwear syntheticresin.

A joint of this type is employed in an articulation cornprising aneye-shaped member having the saidrubber sleeve forced thereinto, acircular-cylindrical pin rotatably inserted in the joint, the diameterof the pin being intermediate between the diameters of the circlesinscribed in and circumscribed on the said polygonal section,respectively, of the resin layer, a lateral abutment on the said pinbearing on the outer circumferential region of the annular layer, and alubricant in the clearance or space defined by the joint, pin andabutment.

Further characteristic features, advantages and opera tion of theimproved joint will be understood from the appended descriptionreferring to the accompanying drawing, wherein:

FIG. l is an axial sectional view of an articulation incorporating apair of improved joints,

FIG. 2 is a part cross sectional view on the broken line II-II of FIG.l,

FIG. 3 is an axial sectional View of one of the possible embodimentsofthe improved joint,

FIGURES 4 and 5 show diagrammatically two preferred inner profiles ofthe improved joint,

FIG. 6 is a part axial sectional View of a further embodiment,

11731519191 Patented Apr. 28., 1964 ICC FIG. 9 is a similar sectionalview of the joint according to FIG. S in its assembled condition.

ln the figures, similar or equivalent parts are denoted by similarreference numerals in which the last digit denotes the figure in orderto avoid a repeated description thereof.

Referring rst to FIGS. l and 2, the articulation as shown comprises arst member having an aperture extending therethrough, for example oneillustration or embodiment of the invention comprises a cylindricaleyeshaped member 10 on a connecting rod or link 11, coaxially arrangedwith a pin member 12 comprising a steel bolt having a head 13 and ascrew threaded end 14 on which a nut 15 is screwed. The bolt 12 extendswith an accurate lit through a pair of aligned circular apertures inabutments or branches 16a, 16b of a strap 16 articulated to the link 11about the axis 17 of the bolt 12. The mutual spacing of the branches16a, 16h of the strap 16 exceeds the axial length of the eye-shapedmember 1li.

Resiliency of the articulation is aorded by two resilient joints 18, 18identical with each other, aligned on the axis 17. The joints eachcomprise a rubber sleeve 19 lhaving at one end an integral radial flangeZtl. The two sleeves are forced in the opposite ends of the eye-shapedmember 10, their axial length being such as to leave a central annularclearance 21 between their near ends when the flanges 20 bear on theirassociated front end surfaces on the member 10.

The sleeves 19 are each lined with a flexible tubular layer 22 of apolyamide resin, the front surface of the hanged end of each sleevebeing outwardly flared and coated with a iiexible annular layer 23 ofsimilar resin copying the said flare. As will be seen in FIG. l, thebore of the annulus 23 somewhat exceeds the diameter oi the bolt 12. Thelayers 22, 23 are bonded to the sleeve 19 on vulcanization of thelatter. In the assembled condition, as shown in FIG. l, the flanges 2t)on the two sleeves 19 are axially pressed by their respective branches16a, 16b against their associated front surfaces on the member 10, sothat a circumferential annular region on the front surface on eachannulus 25 bears under a given axial pressure against an abutmentsurface comprising the respective branch 16a, 16h, respectively, on thestrap 16.

The inner surface 22a on the layer 22 is oi a regular prism-atie shape;in the speciiic case, the cross sectional prole of this surface isdodecagonal with straight sides, two of lthe latter being denoted by 22aand 22a" in FIG. 4. The diameter of the bolt 12 has a value intermediatebetween the diameters d :and D of the circles inscribed andcirournsoribed, respectively, on the polygonal proiile and is in anycase so proportioned las to make Contact with the sleeve alongyangularly spaced points and to leave between the bolt and each of thelongitudinal edges of the prismatic surface 22a a clearance 24, FIGS. 2and 4, extending axially orf the sleeve from one end off thearticulation to the other `and connecting at one end with the annularspace 25, FIG. 1, between the branch 16a and annulus 23 of polyamideresin, and at its other end with the middle annular space 21. Duringassembly of the [articulation the regions 24 and spaces 21, 25 areiilled with a thick lubricant, such Ias graphitated grease.

In operation the `above described articulation distinguishes from priorconstructions in the following respect.

In known constructions the lubricant is constantly in a static conditionin one or a plurality of supply recesses. When the `lilm of lubricantinitially provided between the slidably engaged surfaces is about to beexhausted, the supply recesses are not in a condition to deliver thegrease therein in the absence of a dyn-amic action capable of expelling0r pumping therefrom the necessary grease supplement required tomaintain lubrication of the said surfaces. In mos-t cases the greaseissues from the recesses only [on la substantial rising temperatureoriginating from friction `and hysteresis `of the rubber in operation,that is, when :the friction surfaces begin to be deteriorated. Once suchdeterioration is started, frictions increase and the grease whichbecomes unduly iiui'd owing to heating always succeeds in rin-ding apath for flowing away from the articulation.

According to this invention lthe grease reserves in the cavi-ties 2l,24, 25 are constantly subjected -to pulsatory dynamic factions whicheffect pumping along the edge regions 24. By way of example, when theeye-shaped member l@ in FIG. l vundergoes a thrust towards the left, thecavity 25 `adjacent the branch Ma is somewhat squeezed in lan -axialdirection, the grease therein contained flowing over the `edge region 24towards the middle lannular space 21. At the same time the cavity 25adjacent the branch 16h is released in an axial direction and becomescapable of receiving a small grease supply from the middle space 21through ythe edge regions 24 in its respective joint i8. Reverseprocesses occur when the eye-shaped member lil undergoes Va thrusttowards the right. It will moreover be clear that other mutualvibrations yof the eye-.shaped member lt) and unit l2, i6 effect pumpingin a similar manner as described above, whereby the grease reserves arenever in a quiescent state, and undergo pulsa-tory pressures causing thelubricant to iiow .through fall the cavities 21, 24, 25, therebyrenewing the lubricant film between the surfaces 22a and bolt l2. Itwill moreover be clear that pulsations undergone by Vthe Iannular liaredcavities 25 result in renewing lubricant between each of the annuli 23and its respective strap: 15a, leb without, however, any flow ofLubricant to the outside, since the lubricant pressure is releasedtowards the middle annular cavity 21.

It is not strictly necessary for the sides, such as 22a', 22a :of lthepolygonal prole to be rectilinear. The said sides can even be curved, asshown at 122', 122 in FIG. 5, their convexity being turned towards theaxis of articulation. The radius -R of curvature of these :side should,however, always be a substantial one, possibly not smaller than half thediameter d yof the inscribed circle, in order to aiiord, see FIGS. 4Iand 5, both a satisfactory support for the bolt 12 and an easy tailingof l`the lubricant from the edge regions 244, 255 by the bolt 12.

The resilient joint shown in FIG. 3 comprises a sleeve 193 in 4additionto the end flange 2% a further ilmge 120 at the opposite end, likewiseprovided with an -annular layer 2331of polyamide resin, the 'arrangementbeing symmetrical with respect to the middle transverse plane 30. Thisjoint can be employed .in the structure shown in FIG. 1 as a substitutefor fthe two joints 18, 18 shown. The lubricant supply is then of coursereduced on account fof the absence of the middle annular cavity 21.

The joint shown in FIGS. 6 and` 7 is similar to the joints 18, 18 inFIG. 1, but for the provision of an inner circumferential lip 32 at theend of :the sleeve 196 opposite the flange 266 Iand resin layer 236. Thelip 3-2 which is integral with the sleeve is of a bead form and mergesinto the sleeve =19 by' 'a flexible thin annular region 32a integraltherewith. The -bore of the lip 32 is smaller than the diameter d, FIG.4, of the circle inscribed in the polygonal contour of the surfaces 226,226e, 226a', 226e. IIt will be seen in FIG. 7 .that the lip 32 tightlyencircles` the bolt 12 preventing escape of lubricant from the supplyrecesses such as 24, 25, see also FIG. 4.

In the embodiment shown in FIGS. 8 and 9 the rubber sleeve 198 is formedat one end with an integral f lange 208 4and is lined by a liexibletubular layer 223 of a synthetic resin of polygonal cross sectionalshape, the front surface of the flanged end of the sleeve aringoutwardlyand having a flexible annular coating 238 of similar resincopying the abovementioned flare, integral with the tubular layer 228llining the rubber sleeve 198.

The sleeve 1918 is formed at its end opposite the flange 2&8 with v'acircumferential lip 323 integral with the sleeve, merging into thelatter by a exible thin annular region 328:1.

The inner diameter of lthe lip 32S is smaller than the diameter of thecircle inscribed in the polygonal contour of the inner surface of thetubular layer 22S.

The circumferential surface of the liange 2tlg comprises acircumferential lip 40 of a saw-tooth prolile.

A disc 41 of a rigid material, such as sheet iron is formed with acentral aperture 42 and a circumferential cylindrical flange e3, theaxial length of which is intermediate between the thickness of the lip4G and of the flange 203, respectively.

The diameter of the aperture 42 equals the diameter of the bolt (notshown) in the articulation, the inner diameter of the cylindrical ilange43 being intermediate between the outer diameter of the lip 4? anddiameter of the ange 29S.

On assembly the cylindrical ilange i3 is forced on the lip 40 which isencased by the flange 43 sealing against access of foreign bodies, suchas dust and mud, between the disc 4l and layer 23S, ultimately betweenthe tubular layer 223 and the bolt in the bore 42.

in operation of the articulation shown in FIGS. 8 and 9, since the resinlining the sleeve is of a modulus of elasticity of an order of about 10Utimes the modulus of elasticity of the rubber, radial deformations underload actually occur at the expense of the rubber only, so that theannular resin layer 23S follows the radial movements of the bolt.

The annular lip 4) likewise follows the radial move ments of the bolttogether with the rigid disc 41, the seal against access of foreignbodies being eicient even under substantial radial deformations of thesleeve 193.

What l claim is:

1. A resilient self-lubricating joint comprising a first member havingan aperture extending therethrough, a resilient tubular bushing mountedin said aperture and having an axial bore and at opposite ends thereofradial anges, said bore and flanges extending together axially on saidbushing a distance greater than the effective length of said aperture,said radial anges each having an .inner surface abutting on said lirstmember and an outer surface iiaring outwardly at an oblique angle fromsaid axial bore and said bushing, means dening abutments ybearing onouter marginal edge portions of said radial llanges respectively, saidbushing axial bore having a polygonal coniiguration in cross section,elongated means extending through said axial bore and said abutmentsmaking at least line contact axially along said bore at points spacedangularly and dening jointly With said bushing lubricantreceiving,axially extending angularly spaced separate spaces and dening jointlywith said abutments and said bushing lianges annular lubricant-receivingspaces at said opposite ends of said bushing outwardly of said anges andin communication with said axially extending spaces, said axiallyextending spaces extending the fuil axial length of said bushing bore toprovide said communication with said annular spaces, whereby relativeradial movement of said means extending through said bore andsaidbushing and relative axial movement of said bushing and saidabutments causes pumping of lubricant 1n said spaces thereby toself-lubricate said joint.

2. A resilient self-lubricating joint comprising a first member havingan aperture extending therethrough, a resilient tubular bushing mountedin said aperture and having an axial bore and at opposite ends thereofradial lianges, said bore and flanges extending together axially on saidbushing a distance greater than the effective length of said aperture,said radial ilanges each having an lnner annular surface abutting onsaid first member and an outer annular surface flaring outwardly at anoblique angle from said axial bore and said bushing, means deliningabutments bearing on outer marginal edge portions of the outer annularsurfaces of said flanges respectively, said bushing axial bore having apolygonal configuration in cross section, elongated means extendingthrough said axial bore and said abutments making at least line Contactaxially along said bore at points spaced angularly and dening jointlywith said bushing lubricantreceiving, axially extending, angularlyspaced separate spaces and defining jointly with said abutments and saidbushing fianges annular lubricant-receiving spaces at said opposite endsof said bushing outwardly of said flanges and in communication with saidaxially extending spaces, said axially extending spaces extending thefull axial length of said bushing bore to provide said communicationwith said annular spaces, whereby relative radial movement of said meansextending through said bore and said bushing and relative axial movementof said bushing and said abutments causes pumping of lubricant in saidspaces thereby to self-lubricate said joint.

3. A resilient self-lubricating joint comprising a first member havingan aperture extending therethrough, a resilient tubular bushing mountedin said aperture and having resin-covered inner surfaces defining anaxial bore and at opposite ends thereof radial flanges, said bore andanges extending together axially on said bushing a distance greater thanthe effective length of Said aperture, said radial anges each having aninner annular surface abutting on said first member and an outerresin-covered annular surface flaring outwardly at an oblique angle fromsaid axial bore and said bushing, means defining abutments bearing onouter marginal edge portions of said radial flanges respectively, saidbushing axial bore having a polygonal configuration in cross section,elongated means extending through said axial bore and said abutmentsmaking `at least line contact with said inner surfaces axially alongsaid bore at points spaced angularly and defining jointly with saidbushing lubricant-receiving, axially extending, angularly spacedseparate spaces and defining jointly with said abutments and saidbushing fianges annular lubricant-receiving spaces at said opposite endsof said bushing outwardly of said auges and in communication with saidaxially extending spaces, said axially extending spaces extending thefull axial length of said bushing bore to provide said communicationwith said annular spaces, whereby relative radial movement of said meansextending through said bore and said bushing and relative axial movementof said bushing and said abutments causes pumping of lubricant in saidspaces thereby to self-lubricate said joint.

4, A resilient self-lubricating joint according to claim 3, in whichsaid resin-covered inner surfaces defining said bore comprise a layer ofsynthetic, anti-friction resin, and in which said outer resin-coveredannular surface flaring outwardly comprises a layer of said synthetic,antifriction resin spaced from the first-mentioned layer of resin.

5. A resilient self-lubricaintg joint according to claim 3, in whichsaid elongated means extending through said bore comprises a boltcircular in cross section, and including means threaded on said bolt foradjustably varyingr the pressure with which said abutments bear on saidradial anges.

6. A resilient self-lubricating joint according to claim 3, in whichsaid bushing comprises two, coaxial, sleeve portions spaced from eachother defining a lubricantreceiving annular space therebetween, each ofsaid sleeve portions having a respective one of said flanges integraltherewith.

7. A resilient self-lubricating joint according to claim 3, in whichsaid bushing comprises a sleeve intermediate said fianges and integraltherewith.

References Cited in the file of this patent UNITED STATES PATENTS1,254,909 Howe Jan. 29, 1918 2,797,929 Herbenar July 2, 1957 2,876,029Latzen Mar. 3, 1959 3,039,831 Thomas June 19, 1962 3,072,448 Melton etal. lan. 8, 1963 FOREIGN PATENTS 12,292 Australia May 18, 1934

1. A RESILIENT SELF-LUBRICATING JOINT COMPRISING A FIRST MEMBER HAVINGAN APERTURE EXTENDING THERETHROUGH, A RESILIENT TUBULAR BUSHING MOUNTEDIN SAID APERTURE AND HAVING AN AXIAL BORE AND AT OPPOSITE ENDS THEREOFRADIAL FLANGES, SAID BORE AND FLANGES EXTENDING TOGETHER AXIALLY ON SAIDBUSHING A DISTANCE GREATER THAN THE EFFECTIVE LENGTH OF SAID APERTURE,SAID RADIAL FLANGES EACH HAVING AN INNER SURFACE ABUTTING ON SAID FIRSTMEMBER AND AN OUTER SURFACE FLARING OUTWARDLY AT AN OBLIQUE ANGLE FROMSAID AXIAL BORE AND SAID BUSHING, MEANS DEFINING ABUTMENTS BEARING ONOUTER MARGINAL EDGE PORTIONS OF SAID RADIAL FLANGES RESPECTIVELY, SAIDBUSHING AXIAL BORE HAVING A POLYGONAL CONFIGURATION IN CROSS SECTION,ELONGATED MEANS EXTENDING THROUGH SAID AXIAL BORE AND SAID ABUTMENTSMAKING AT LEAST LINE CONTACT AXIALLY ALONG SAID BORE AT POINTS SPACEDANGULARLY AND DEFINING JOINTLY WITH SAID BUSHING LUBRICANTRECEIVING,AXIALLY EXTENDING ANGULARLY SPACED SEPARATE SPACES AND DEFINING JOINTLYWITH SAID ABUTMENTS AND SAID BUSHING FLANGES ANNULAR LUBRICANT-RECEIVINGSPACES AT SAID OPPOSITE ENDS OF SAID BUSHING OUTWARDLY OF SAID FLANGESAND IN COMMUNICATION WITH SAID AXIALLY EXTENDING SPACES.